What causes the planet to get warmer and what is being done to stop it?
FROM burning fossil fuels to agreeing a strategy for the future, here we answer the key climate change questions...
What is global warming and how is it caused?
Over the past 150 years, industrialised countries have been burning large amounts of fossil fuels, such as oil and gas.
Once released into the atmosphere, these gases, such as carbon dioxide (CO2), act like a blanket, trapping heat from the sun. That warms the Earth – known as the greenhouse effect.
Scientists are also concerned about methane, nitrous oxide, ozone and chlorofluorocarbons (CFCs) which all cause significant additional heating.
Deforestation in the Amazon and Borneo also contributes as trees absorb huge amounts of carbon dioxide and release oxygen back to the atmosphere.
What are the effects of greenhouse gases?
As the planet warms, weather will become more extreme and unpredictable with droughts, floods, heat waves, extreme storms, more wildfires, intense hurricanes and other global disasters.
Can anything be done? Yes, but scientists say rapid and far-reaching change is needed.
For decades, experts argued that the rise in global temperature must be kept below 2C by the end of this century to avoid the worst impacts.
But now scientists say 1.5C is a far safer limit for the planet.
Fossil fuel consumption, the main producer of greenhouse gases, needs to change most.
CO2 emissions must be cut to 45% of 2010 levels by 2030 to curb warming at 1.5C. By 2050 we need to be at “net zero”, meaning any remaining CO2 pumped into the atmosphere needs to be sucked back out by trees and technologies that capture carbon from the air and store it. Some scientists say that we are now headed for a rise of between 3C and 4C by 2100. This could lead to sea levels rising up to 200ft, leaving large parts of the planet uninhabitable.
What is the Paris Agreement? The agreement adopted in 2015 is designed to keep warming well below 2C.
It united 197 nations, including the UK, but Donald Trump, below, has now begun to withdraw the US, one of the world’s biggest sources of emissions, from the accord.
Does half a degree make a difference?
Once we hit 2C experts say there will be almost no coral reefs left, the Arctic will be ice-free in summer once a decade, and huge numbers of animals and plants will be extinct.
The impact for humans will be huge, especially in coastal regions of Bangladesh and Vietnam, and island states.
Who are the big polluters? The US was the world’s largest CO2 producer but has been overtaken by China, with the EU in third, followed by India and then Russia.